Andromeda
And · genitive Andromedae · northern sky
At a glance
- Catalogued stars
- 155
- Visible to the eye
- 155 stars
- Brightest star
- Alpheratz (2.07)
- Best seen
- September
- Declination span
- +23.4° to +48.6°
- Nearest star
- HD 10307 · 41.5 ly
Visible from everywhere north of about 41°S.
When and where to look for Andromeda
Andromeda crosses the meridian — its highest point in the sky — at local midnight around September, which makes the months from August to October the easiest time to find it in the evening. It spans declinations +23.4° to +48.6°, so visible from everywhere north of about 41°S.
The quickest way to find it is to open the live AR sky map and point your phone at the sky — if Andromeda is above your horizon right now, its figure is drawn in the position it genuinely occupies above you.
Brightest stars in Andromeda
| Star | Mag | Type | Distance |
|---|---|---|---|
| Alpheratz21Alp And | 2.07 | B9p | 97 ly |
| Mirach43Bet And | 2.07 | M0IIIvar | 197.4 ly |
| Almach57Gam1And | 2.10 | B8V | 393 ly |
| 31Del And | 3.27 | K3III... | 105.5 ly |
| Nembus51 And | 3.59 | K3III | 177.2 ly |
| 1Omi And | 3.62 | B6pv SB | 686.6 ly |
Magnitude runs backwards: lower numbers are brighter, and anything below about 6.5 is beyond the naked eye under a dark sky.
What Andromeda is made of
The catalogue lists 155 stars within Andromeda, of which 155 are magnitude 6.5 or brighter — the limit of what an unaided eye picks up under a genuinely dark sky. The rest need binoculars or a telescope.
Spectral make-up
Spectral class is a temperature ordering, running from O at around 30,000 K down to M below 3,500 K. A constellation is a direction, not a group, so this is simply what happens to lie along that line of sight.
The closest catalogued star in this direction is HD 10307 at 41.5 light years. The most distant is HD 11884 at roughly 2,219 light years — stars that appear side by side here are nothing of the sort.
Deep-sky objects in Andromeda
- Andromeda Galaxy — galaxy
These are marked on the sky map, so you can see where they sit relative to the constellation figure in real time.